Field of the Invention
The present invention relates to a fuel injection control device.
Description of Related Art
In the related art, as a technique of improving the fuel economy performance and the environmental protection performance of a vehicle, a bi-fuel system is known which selectively switches between liquid fuel such as gasoline and gaseous fuel such as compressed natural gas (CNG) and supplies the selected fuel to a single engine. In order to reduce development costs, there is a case where the bi-fuel system is constructed in a form in which a new gas injection system is added to an existing gasoline injection system.
Japanese Unexamined Patent Application, First Publication No. 2013-148006 discloses a bi-fuel system in which with respect to an existing electronic control device which outputs a first pulse signal for controlling the injection quantity of gasoline, a new electronic control device which converts the first pulse signal to a second pulse signal suitable for gaseous fuel is provided. In addition, the first pulse signal is a pulse signal which has a pulse width corresponding to the injection quantity of gasoline and is used in order to drive a gasoline injector, and the second pulse signal is a pulse signal which has a pulse width suitable for gaseous fuel and is used in order to drive a gas injector.
Specifically, in the bi-fuel system disclosed in Japanese Unexamined Patent Application, first Publication No. 2013-148006, in the new electronic control device, a normally-on switch is provided between an input terminal and an output terminal of the first pulse signal and performs the following control, thereby avoiding stopping of fuel supply to an engine; at the time of injection of gasoline, maintaining the switch in an ON state and supplying the first pulse signal from the input terminal to a gasoline injector through the switch and the output terminal, and at the time of injection of gaseous fuel, switching the switch to an OFF state, making the first pulse signal from the input terminal branch at a stage previous to the switch, converting the branched first pulse signal to the second pulse signal, and supplying the second pulse signal to a gas injector.